CN111158143B

CN111158143B - Micro projection light engine for near-eye display device

Info

Publication number: CN111158143B
Application number: CN201811322526.6A
Authority: CN
Inventors: 郑光; 陈杭; 郝希应; 陈远; 胡增新
Original assignee: Sunny Optical Zhejiang Research Institute Co Ltd
Current assignee: Sunny Optical Zhejiang Research Institute Co Ltd
Priority date: 2018-11-08
Filing date: 2018-11-08
Publication date: 2021-06-04
Anticipated expiration: 2038-11-08
Also published as: CN111158143A

Abstract

A miniature projection light engine for a near-eye display device. The micro projection light engine includes a light source system for emitting polarized light having the same polarization state along a predetermined direction, a display unit for modulating the polarized light into polarized light carrying image information, an imaging system for projecting the polarized light carrying image information, and a relay system. The relay system is arranged among the light source system, the display unit and the imaging system, and the light source system and the imaging system are respectively positioned at the opposite sides of the relay system, wherein the relay system is used for changing the propagation direction of the polarized light from the light source system so as to enable the polarized light to propagate to the display unit; wherein the relay system is further configured to change a propagation direction of the polarized light carrying the image information from the display unit so that the polarized light carrying the image information can propagate to the imaging system along the predetermined direction.

Description

Micro projection light engine for near-eye display device

Technical Field

The present invention relates to the field of projection technology, and more particularly to a miniature projection light engine for a near-eye display device.

Background

In recent years, the advent of micro display chip technology has made possible miniaturization and high-resolution projection display. With the continuous development of projection display technology and market demand, wearable micro projection light engines with large view field, high imaging quality and small volume are more and more emphasized, especially in the fields of developing fire-heat Augmented Reality (AR), Near-eye display (NED) and wearable at present.

However, the existing micro projection light engine generally includes a light source system, a relay lens group, a display chip and a projection imaging system, wherein the relay lens group is located in an emission path of the light source system, and the display chip and the projection imaging system are located on opposite sides of the relay lens group, which results in a large size and volume of the existing micro projection light engine, which is difficult to meet the market demand for a small-volume micro projection light engine, and especially cannot be widely applied and popularized in the fields of augmented reality, near-eye display, wearable, and the like.

Disclosure of Invention

It is an object of the present invention to provide a miniature projection light engine for a near-eye display device that meets the market demand for a miniature projection light engine of small volume.

It is another object of the present invention to provide a micro projection light engine for a near-eye display device, wherein in an embodiment of the present invention, the micro projection light engine employs an innovative light path design to achieve the requirements of small size and light weight.

Another object of the present invention is to provide a micro projection light engine for a near-eye display device, wherein in an embodiment of the present invention, a relay system of the micro projection light engine is designed in a catadioptric manner, which is beneficial to make the relay system compact and small in size.

It is another object of the present invention to provide a micro projection light engine for a near-eye display device, wherein, in an embodiment of the present invention, the micro projection light engine has a catadioptric relay path to further reduce the size or volume of the micro projection light engine while ensuring that a sufficiently long relay path is provided.

Another object of the present invention is to provide a micro projection light engine for a near-eye display device, wherein, in an embodiment of the present invention, an imaging system of the micro projection light engine is designed in a catadioptric manner, which is beneficial to make the imaging system compact and small in size.

It is another object of the present invention to provide a micro projection light engine for a near-eye display device, wherein, in an embodiment of the present invention, the micro projection light engine has a catadioptric imaging path to reduce the size or volume of the micro projection light engine while ensuring that a sufficiently long imaging path is provided.

It is another object of the present invention to provide a micro projection light engine for a near-eye display device, wherein, in an embodiment of the present invention, the overall volume of the micro projection light engine is small enough to be applied and popularized in the fields of augmented reality, near-eye display and wearable.

It is another object of the present invention to provide a micro projection light engine for a near-eye display device, wherein, in an embodiment of the present invention, the micro projection light engine has a linear structure, which helps to reduce the lateral dimension of the micro projection light engine.

It is another object of the present invention to provide a miniature projection light engine for a near-eye display device, wherein, in an embodiment of the present invention, the miniature projection light engine is portable, which is suitable for being widely used in the conventional projection field.

It is another object of the present invention to provide a micro projection light engine for a near-eye display device, wherein in an embodiment of the present invention, the micro projection light engine is adapted to project polarized light carrying image information into a waveguide of the near-eye display device, so as to project the polarized light carrying image information into a human eye for imaging through the waveguide.

It is another object of the present invention to provide a miniature projection light engine for a near-eye display device, wherein expensive materials or complex structures are not required in the present invention in order to achieve the above objects. Accordingly, the present invention successfully and efficiently provides a solution that not only provides a simple micro projection light engine for near-eye display devices, but also increases the practicality and reliability of the micro projection light engine for near-eye display devices.

To achieve at least one of the above objects or other objects and advantages, the present invention provides a micro projection light engine, comprising:

a light source system for emitting polarized light having the same polarization state in a predetermined direction;

the display unit is used for modulating the polarized light into the polarized light carrying image information;

an imaging system for projecting polarized light carrying image information; and

a relay system, wherein the relay system is disposed between the light source system, the display unit and the imaging system, and the light source system and the imaging system are respectively located at opposite sides of the relay system, wherein the relay system is configured to change a propagation direction of polarized light from the light source system so that the polarized light propagates to the display unit; wherein the relay system is further configured to change a propagation direction of the polarized light carrying the image information from the display unit so that the polarized light carrying the image information can propagate to the imaging system along the predetermined direction.

In an embodiment of the present invention, the relay system includes a relay polarization beam splitting system and a relay catadioptric system, wherein the relay polarization beam splitting system is disposed between the light source system and the imaging system, and the display unit and the relay catadioptric system are respectively located on two opposite sides of the relay polarization beam splitting system, wherein the display unit is further configured to reflect the polarized light carrying the image information back to the relay polarization beam splitting system, and the relay catadioptric system is configured to reflect the polarized light refracted from the relay polarization beam splitting system back to the relay polarization beam splitting system, so as to define a catadioptric relay optical path forming the relay system between the light source system and the display unit, so that the polarized light can propagate to the display unit along the catadioptric relay optical path.

In an embodiment of the present invention, the relay catadioptric system includes a relay light conversion element and a relay light reflection element, wherein the relay light conversion element is located between the relay polarization beam splitting system and the relay light reflection element, wherein the relay light reflection element is configured to reflect the polarized light emitted from the relay polarization beam splitting system back to the relay polarization beam splitting system so that the polarized light passes through the relay light conversion element twice, and wherein the relay light conversion element is configured to convert the polarized light passing through twice into polarized light having another polarization state.

In an embodiment of the invention, the relay light conversion element is an 1/4 wave plate, and the relay light reflection element is a concave mirror.

In an embodiment of the present invention, the relay polarization beam splitting system includes a first relay right-angle prism, a second relay right-angle prism, and a relay polarization beam splitting film, wherein the relay polarization beam splitting film is disposed between an inclined surface of the first relay right-angle prism and an inclined surface of the second relay right-angle prism to form the relay polarization beam splitting system having a rectangular cross section, wherein the relay polarization beam splitting film is configured to allow P-polarized light to pass therethrough and reflect S-polarized light to change a propagation direction of the S-polarized light.

In an embodiment of the invention, the relay polarization beam splitting film is a PBS film.

In an embodiment of the present invention, the relay polarization beam splitting system has a relay incident surface, a relay emergent surface parallel to the relay incident surface, a relay reflecting surface perpendicular to the relay incident surface, and a relay display surface perpendicular to the relay incident surface, wherein the light source system corresponds to the relay incident surface; wherein the relay inflexion system corresponds to the relay inflexion surface; wherein the display unit corresponds to the relay display surface; wherein the imaging system corresponds to the relay exit face.

In an embodiment of the present invention, the relay incident surface and the relay display surface of the relay polarization beam splitting system intersect with the relay polarization beam splitting film, and the relay exit surface and the relay reflection surface of the relay polarization beam splitting system intersect with the relay polarization beam splitting film, so that S-polarized light from the light source system is reflected by the relay polarization beam splitting film to propagate from the relay incident surface to the relay reflection surface while being bent, and then after being converted into P-polarized light by the relay reflection system and being bent back to the relay reflection surface, the P-polarized light passes through the relay polarization beam splitting film to propagate from the relay reflection surface to the display unit on the relay display surface.

In an embodiment of the present invention, the relay system further includes a relay lens assembly, wherein the relay lens assembly is disposed between the relay incident plane of the relay polarization beam splitting system and the light source system, and is used for adjusting a degree of convergence of the polarized light from the light source system.

In an embodiment of the invention, the relay system further includes a relay polarization filtering unit, where the relay polarization filtering unit is disposed between the relay lens assembly and the relay incident plane of the relay polarization beam splitting system, and is configured to filter stray light in the S-polarized light.

In an embodiment of the invention, the relay polarization filtering unit is an S polarizer.

In an embodiment of the present invention, the imaging system includes an imaging polarization beam splitting system and an imaging catadioptric system, wherein the imaging polarization beam splitting system is located between the imaging catadioptric system and the relay system, and wherein the imaging catadioptric system is configured to reflect the polarized light carrying the image information refracted by the imaging polarization beam splitting system back to the imaging polarization beam splitting system, so as to define a catadioptric imaging optical path forming the imaging system through the relay system and the imaging system, so that the micro projection light engine can project the polarized light carrying the image information along the catadioptric imaging optical path.

In an embodiment of the present invention, the imaging catadioptric system includes an imaging light conversion element and an imaging light reflection element, where the imaging light conversion element is located between the imaging light reflection element and the imaging polarization beam splitting system, where the imaging light reflection element is configured to reflect the polarization light carrying image information emitted from the imaging polarization beam splitting system back to the imaging polarization beam splitting system, so that the polarization light carrying image information passes through the imaging light conversion element for a second time, and the imaging light conversion element is configured to convert the polarization light carrying image information passing through the imaging light conversion element for a second time into polarization light carrying image information having another polarization state.

In an embodiment of the invention, the imaging light conversion element is an 1/4 wave plate, and the imaging light reflection element is a concave mirror.

In an embodiment of the invention, the imaging polarization beam splitting system includes a first imaging right-angle prism, a second imaging right-angle prism, and an imaging polarization beam splitting film, wherein the imaging polarization beam splitting film is disposed between an inclined plane of the first imaging right-angle prism and an inclined plane of the second imaging right-angle prism to form the imaging polarization beam splitting system with a rectangular cross section, and the imaging polarization beam splitting film is configured to allow P-polarized light carrying image information to transmit therethrough and reflect S-polarized light carrying image information to turn the S-polarized light carrying image information.

In one embodiment of the present invention, the imaging polarization beam splitting system has an imaging incident surface, an imaging emergent surface perpendicular to the imaging incident surface, and an imaging reflecting surface perpendicular to the imaging incident surface, wherein the imaging catadioptric system corresponds to the imaging catadioptric surface and the relay system corresponds to the imaging entrance surface, wherein the catadioptric imaging optical path extends from the relay display surface to the relay exit surface in a bending manner, and then extends from the relay exit surface to the imaging entrance surface, then, the refraction and reflection type imaging optical path is reflected by the imaging polarization beam splitting film to extend from the imaging incidence surface to the imaging refraction and reflection surface in a bending way, and finally after being refracted and reflected by the relay refraction and reflection system to the imaging refraction and reflection surface, and then the light passes through the imaging polarization beam splitting film to extend from the imaging refraction and reflection surface to the imaging emergent surface.

In an embodiment of the invention, the imaging system further includes an imaging polarization filtering unit, where the imaging polarization filtering unit is disposed between the relay system and the imaging incident plane of the imaging polarization beam splitting system, and is configured to filter stray light in the S-polarized light carrying image information from the relay system.

In an embodiment of the invention, the imaging polarization filtering unit is an S polarizer.

In one embodiment of the present invention, the imaging polarization beam splitting system has an imaging incident surface, an imaging emergent surface perpendicular to the imaging incident surface, and an imaging reverse surface parallel to the imaging incident surface, wherein the imaging catadioptric system corresponds to the imaging catadioptric surface and the relay system corresponds to the imaging entrance surface, wherein the catadioptric imaging optical path extends from the relay display surface to the relay exit surface in a bending manner, and then extends from the relay exit surface to the imaging entrance surface, then, the refraction and reflection type imaging optical path passes through the imaging polarization beam splitting film to extend from the imaging incidence surface to the imaging refraction and reflection surface, and finally after being refracted and reflected by the imaging refraction and reflection system to the imaging refraction and reflection surface, and then reflected by the imaging polarization beam splitting film to extend from the imaging refraction and reflection surface to the imaging emergent surface in a bending way.

In an embodiment of the present invention, the imaging system further includes an imaging conversion unit, where the imaging conversion unit is disposed between the imaging incidence plane of the imaging polarization beam splitting system and the relay system, and is configured to convert S-polarized light carrying image information from the relay system into P-polarized light carrying image information incident from the imaging incidence plane.

In an embodiment of the present invention, the image conversion unit is an 1/2 wave plate or a pair of 1/4 wave plates.

In an embodiment of the present invention, the imaging system further includes an imaging lens assembly, wherein the imaging lens assembly includes a first imaging lens group and a second imaging lens group, wherein the first imaging lens group is disposed between the relay system and the imaging conversion unit, and the second imaging lens group is disposed at the imaging exit surface of the imaging polarization beam splitting system.

In an embodiment of the present invention, the imaging system further includes an imaging polarization filtering unit, where the imaging polarization filtering unit is disposed between the imaging conversion unit and the imaging incident plane of the imaging polarization beam splitting system, and is configured to filter stray light in the P-polarized light carrying the image information converted by the imaging conversion unit.

In an embodiment of the invention, the imaging polarization filtering unit is a P-polarizer.

In an embodiment of the invention, the light source system includes at least two light emitting units, a color combining system and a polarization multiplexing system, wherein each of the light emitting units is configured to emit monochromatic light, the color combining system is located between the at least two light emitting units and the polarization multiplexing system, and is configured to combine the monochromatic light emitted by the at least two light emitting units into a combined light, and the polarization multiplexing system is configured to convert the combined light into S-polarized light.

In an embodiment of the present invention, the light source system further includes at least two collimating systems and a light uniformizing system, wherein each collimating system is disposed between the corresponding light emitting unit and the color combining system, and is configured to collimate the monochromatic light emitted by the corresponding light emitting unit; the light homogenizing system is arranged between the color combination system and the polarization multiplexing system and is used for homogenizing the color combination light.

Further objects and advantages of the invention will be fully apparent from the ensuing description and drawings.

These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description, the accompanying drawings and the claims.

Drawings

FIG. 1 is a system diagram of a micro projection light engine according to a preferred embodiment of the present invention.

FIG. 2 is a schematic diagram of the micro projection light engine according to the above preferred embodiment of the present invention.

FIG. 3 is a schematic optical path diagram of the micro projection light engine according to the above preferred embodiment of the present invention.

FIG. 4 is an enlarged schematic view of a relay system of the micro projection light engine according to the above preferred embodiment of the present invention.

FIG. 5A is an enlarged schematic view of an imaging system of the micro projection light engine according to the above preferred embodiment of the present invention.

Fig. 5B shows a variant implementation of the imaging system according to the above preferred embodiment of the invention.

Fig. 6A is a schematic diagram of a near-eye display device according to the present invention.

Fig. 6B is a schematic diagram of another near-eye display device according to the present invention.

Detailed Description

The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.

It will be understood by those skilled in the art that in the present disclosure, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced devices or components must be constructed and operated in a particular orientation and thus are not to be considered limiting.

In the present invention, the terms "a" and "an" in the claims and the description should be understood as meaning "one or more", that is, one element may be one in number in one embodiment, and the element may be more than one in number in another embodiment. The terms "a" and "an" should not be construed as limiting the number unless the number of such elements is explicitly recited as one in the present disclosure, but rather the terms "a" and "an" should not be construed as being limited to only one of the number.

In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "connected" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

In recent years, with the advent of micro display chip technology, miniaturization and high-resolution projection display have become possible. However, in order to obtain higher projection imaging quality, the existing micro projection light engine has to be made large, which results in that the existing micro projection light engine cannot meet the strict requirements of the current augmented reality, near-eye display and wearable product on volume and weight due to its own size or large volume. Therefore, there is a need for a compact projection light engine with a small enough size, light weight, and high imaging quality to meet the market demand.

Referring to fig. 1-5A of the drawings, a miniature projection light engine according to a preferred embodiment of the present invention is illustrated. As shown in fig. 1 to 3, the micro-projection light engine 1 includes a light source system 10, a relay system 20, an imaging system 30 and a display unit 40, wherein the relay system 20 is disposed between the light source system 10, the imaging system 30 and the display unit 40, and the light source system 10 and the imaging system 30 are respectively located at opposite sides of the relay system 20. The light source system 10 is used for emitting polarized light with a specific polarization state along a predetermined direction. The relay system 20 is configured to change the propagation direction of the polarized light from the light source system 10 so that the polarized light propagates to the display unit 40. The display unit 40 is configured to modulate the polarized light into a polarized light carrying image information, and reflect the polarized light carrying image information back to the relay system 20. The relay system 20 is further configured to change the propagation direction of the polarized light carrying the image information, so that the polarized light carrying the image information can propagate to the imaging system 30 along the predetermined direction. The imaging system 30 is used to project the polarized light carrying the image information.

In this way, the propagation direction of the polarized light carrying the image information emitted from the relay system 20 is consistent with the propagation direction of the polarized light emitted from the relay system 20, that is, the light source system 10, the relay system 20 and the imaging system 30 are in the same straight line, so that the micro projection light engine 1 has a straight line structure, so as to reduce the volume or size of the micro projection light engine 1, which is helpful to meet the market demand for a small-volume micro projection light engine.

It is to be noted that, in the present invention, polarized light having S polarization state is simply referred to as S polarized light, and polarized light having P polarization state is simply referred to as P polarized light. For example, the polarized light with a specific polarization state emitted by the light source system 10 may be implemented as S-polarized light, and the polarized light carrying image information may be implemented as, but is not limited to, S-polarized light carrying image information. Of course, in other examples of the present invention, the polarized light carrying the image information can also be implemented as a P-polarized light carrying the image information.

In addition, for clarity of presentationThe variation of various polarization states of light in the light path of the micro-projection light engine 1 is shown in the drawings of the present invention: the S polarized light is denoted by S; with S^*S polarized light representing the image information; p denotes the P polarized light; by P^*P-polarized light representing the image information; and unpolarized light (which may be natural light, monochromatic light, or partially polarized light, etc.) is denoted by S + P.

Specifically, in the preferred embodiment of the present invention, as shown in fig. 2 and 3, the relay system 20 of the micro projection light engine 1 includes a relay polarization beam splitting system 21 and a relay catadioptric system 22, wherein the display unit 40 and the relay catadioptric system 22 are respectively disposed on opposite sides of the relay polarization beam splitting system 21. The display unit 40 is configured to modulate the polarized light into polarized light carrying image information, and reflect the polarized light carrying image information back to the relay polarization beam splitting system 21. The relay refraction and reflection system 22 is configured to refract the polarized light emitted from the relay polarization beam splitting system 21 back to the relay polarization beam splitting system 21 to define a refraction and reflection type relay optical path 200 between the light source system 10 and the display unit 40, so that the polarized light from the light source system 10 propagates along the refraction and reflection type relay optical path 200 to the display unit 40. In this way, the catadioptric relay optical path 200 enables the relay system 20 to provide a sufficiently long relay optical path in a small volume, so as to further reduce the volume or size of the micro projection light engine 1 while ensuring high imaging quality of the micro projection light engine 1, which helps meet the market demand for a small-volume micro projection light engine.

It is noted that the display unit 40 can be, but is not limited to being, implemented as a reflective Lcos panel for modulating the polarized light into the polarized light carrying the image information and reflecting the polarized light carrying the image information. Of course, in other examples of the present invention, the display unit 40 may also be implemented as other types of display chips as long as the polarized light can be modulated and reflected, and the present invention does not further limit the present invention.

Illustratively, in the preferred embodiment of the present invention, as shown in fig. 3 and 4, the relay catadioptric system 22 of the relay system 20 includes a relay light conversion element 221 and a relay light reflection element 222, wherein the relay light conversion element 221 is disposed between the relay light reflection element 222 and the relay polarization beam splitting system 22. The relay light reflection element 222 is configured to reflect the P or S polarized light emitted from the relay light conversion element 221 back to the relay light conversion element 221, so that the P or S polarized light passes through the relay light conversion element 221 twice. The relay light conversion element 221 is configured to convert the P or S polarized light passing through twice into S or P polarized light.

It is noted that, in the preferred embodiment of the present invention, the relay light conversion element 221 can be implemented as, but not limited to, an 1/4 wave plate; the relay light reflecting element 222 may be implemented as, but is not limited to, a concave mirror. Of course, in other examples of the present invention, the relay light conversion element 221 may also be implemented as other types of wave plates or light conversion members as long as the P or S polarized light passing through twice can be converted into the S or P polarized light; the relay light reflection element 222 may also be implemented as another type of mirror or light reflection member, as long as it can reflect the P or S polarized light emitted from the relay polarization beam splitting system 21 back to the relay polarization beam splitting system 21, so that the P or S polarized light passes through the relay light conversion element 221 twice, which is not further limited in the present invention.

In addition, the display unit 40 is used to modulate the P or S polarized light into S or P polarized light carrying image information, and refract the S or P polarized light carrying image information back to the relay polarization beam splitting system 21 in a reflective manner. And the relay polarization beam splitting system 21 functions to reflect the S-polarized light to change the propagation direction of the S-polarized light and allow the P-polarized light to pass therethrough without changing the propagation direction of the P-polarized light. Therefore, according to the above characteristics of the display unit 40, the relay polarization beam splitting system 21 and the relay catadioptric system 22, the catadioptric relay optical path 200 can be designed reasonably to achieve a sufficiently long relay optical path in a small volume, so as to reduce the volume or size of the micro projection light engine 1 while ensuring high imaging quality of the micro projection light engine 1.

Illustratively, as shown in fig. 4, the relay polarization beam splitting system 21 of the relay system 20 has a relay incident surface 2101, a relay exit surface 2102 parallel to the relay incident surface 2101, a relay catadioptric surface 2103 perpendicular to the relay incident surface 2101, and a relay display surface 2104 perpendicular to the relay incident surface 2101, wherein the relay light conversion element 221 of the relay catadioptric system 22 is disposed between the relay light reflection element 222 of the relay catadioptric system 22 and the relay catadioptric surface 2103 of the relay polarization beam splitting system 21, and wherein the display unit 40 is disposed on the relay display surface 2104 of the relay polarization beam splitting system 21 to define the catadioptric relay path 200 through the relay polarization beam splitting system 21 and the relay catadioptric system 22.

Further, the relay incident surface 2101 of the relay polarization beam splitting system 21 corresponds to the light source system 10, and the relay exit surface 2102 corresponds to the imaging system 30 to form the micro projection light engine 1 having a linear structure, contributing to a reduction in size of the micro projection light engine 1.

Thus, when the S-polarized light from the light source system 10 enters the relay polarization beam splitting system 21 from the relay entrance surface 2101, the S-polarized light is reflected by the relay polarization beam splitting system 21 to exit from the relay catadioptric surface 2103; then, the S-polarized light emitted from the relay refraction reverse 2103 is reflected by the relay light reflecting element 222 back to the relay refraction reverse 2103, so that the S-polarized light passes through the relay light conversion element 221 twice; at the same time, the S-polarized light is converted into P-polarized light by the relay light conversion element 221, so that the converted P-polarized light enters the relay polarization beam splitting system 21 from the relay reflecting surface 2103; then, the P-polarized light incident from the relay reflecting surface 2103 passes through the relay polarization beam splitting system 21 to be emitted from the relay display surface 2104; finally, after the P-polarized light emitted from the relay display surface 2104 is modulated into S-polarized light carrying image information by the display unit 40, the S-polarized light carrying image information is reflected back to the relay display surface 2104 by the display unit 40.

In other words, the catadioptric relay optical path 200 of the relay system 20 is first reflected by the relay polarization beam splitting system 21 to extend from the relay incident surface 2101 of the relay polarization beam splitting system 21 to the relay catadioptric surface 2103 with a bend; then, after being reflected back to the relay reflection surface 2103 by the relay reflection system 22, the catadioptric relay optical path 200 passes through the relay polarization beam splitting system 21 to extend from the relay reflection surface 2103 to the relay display surface 2104, so that the polarized light can be catadioptric transmitted to the display unit 40 along the catadioptric relay optical path 200 to be modulated into polarized light carrying image information by the display unit 40, thereby achieving a sufficiently long relay optical path in a small space.

It should be noted that, as shown in fig. 3, after the S-polarized light carrying the image information is reflected by the display unit 40 back to the relay display surface 2104, the S-polarized light carrying the image information is reflected by the relay polarization beam splitting system 21 to propagate from the relay display surface 2104 to the relay exit surface 2102 in a bending manner, and to propagate from the relay exit surface 2102 to the imaging system 30, so as to define a part forming a folded imaging optical path 300 between the display unit 40 and the imaging system 30, and the imaging optical path of the micro projection light engine 1 can also be extended, so as to further improve the imaging quality of the micro projection light engine 1.

More specifically, as shown in fig. 3 and 4, the relay polarization beam splitting system 21 of the relay system 20 includes a first relay right-angle prism 211, a second relay right-angle prism 212, and a relay polarization beam splitting film 213, wherein the relay polarization beam splitting film 213 is disposed between an inclined surface of the first relay right-angle prism 211 and an inclined surface of the second relay right-angle prism 212 to form the relay polarization beam splitting system 21 having a rectangular structure. The relay polarization beam splitting film 213 serves to allow the P-polarized light to pass therethrough, and to reflect the S-polarized light and the image information-carrying S-polarized light to turn the S-polarized light and the image information-carrying S-polarized light.

The two right-angled surfaces of the first relay right-angle prism 211 are respectively defined as the relay incident surface 2101 and the relay catadioptric surface 2103 of the relay polarization beam splitting system 21, and the two right-angled surfaces of the second relay right-angle prism 212 are respectively defined as the relay exit surface 2102 and the relay display surface 2104 of the relay polarization beam splitting system 21. At this time, the relay exit surface 2102 is parallel to the relay entrance surface 2101, and the relay catadioptric surface 2103 is parallel to the relay display surface 2104, while the relay exit surface 2102 and the relay catadioptric surface 2103 intersect with the relay polarization beam splitting film 213, and the relay entrance surface 2101 and the relay display surface 2104 intersect with the relay polarization beam splitting film 213.

It is to be noted that the relay polarization beam splitting film 213 may be, but not limited to, implemented as a PBS film for allowing P-polarized light to pass therethrough and preventing S-polarized light carrying image information and S-polarized light from passing therethrough to reflect the S-polarized light carrying image information and the S-polarized light carrying image information to change the propagation directions of the S-polarized light and the S-polarized light carrying image information.

Thus, the S-polarized light entering from the relay incident surface 2101 is reflected by the relay polarization beam splitter film 213 to exit from the relay reflection surface 2103; then, the S-polarized light emitted from the relay refraction and reflection surface 2103 is converted into the P-polarized light by the relay refraction and reflection system 21, and the P-polarized light is reflected to the relay refraction and reflection surface 2103; then, the P-polarized light entering from the relay reflecting surface 2103 passes through the relay polarization beam splitter film 213 and exits from the relay display surface 2104; finally, the P-polarized light emitted from the relay display surface 2104 is modulated into S-polarized light carrying image information by the display unit 40.

In other words, the catadioptric relay optical path 200 extends from the relay incident surface 2101 to the relay polarizing beam splitter film 213, and then extends from the relay polarizing beam splitter film 213 to the relay catadioptric surface 2103; then, the catadioptric relay optical path 200 extends from the relay catadioptric surface 2103 to the relay display surface 2104 in a catadioptric manner, so as to extend the length of the catadioptric relay optical path 200, which helps to further reduce the volume or size of the micro-projection light engine 1.

It is to be noted that, as shown in fig. 3 and 4, the S-polarized light carrying the image information modulated by the display unit 40 will be reflected by the display unit 40 back to the relay display surface 2104, and then the S-polarized light carrying the image information incident from the relay display surface 2104 is reflected by the relay polarization beam splitting film 213 to be emitted from the relay exit surface 2102, so as to be transmitted to the imaging system 30. In other words, a part of the catadioptric imaging optical path 300 is reflected by the relay polarization beam splitting film 213 to extend from the relay display surface 2104 to the relay exit surface 2102 in a bending manner, and then extends from the relay exit surface 2102 to the imaging system 30, so as to extend the length of the catadioptric imaging optical path 300, which helps to further reduce the size or volume of the micro-projection light engine 1.

Preferably, each of the first and second relay right-

angle prisms

211 and 212 is implemented as a isosceles right-angle prism so that an included angle between the relay polarization beam splitter film 213 and the relay incident surface 2101 is 45 degrees. In this way, the included angle between the relay polarization beam splitter film 213 and the relay exit surface 2102, the relay catadioptric surface 2103 and the relay display surface 2104 is also 45 degrees, so that the S-polarized light perpendicularly incident on the relay incident surface 2101 is reflected by the relay polarization beam splitter film 213 to perpendicularly exit the relay catadioptric surface 2103, and the S-polarized light carrying the image information perpendicularly incident on the relay display surface 2104 is reflected by the relay polarization beam splitter film 213 to perpendicularly exit the relay exit surface 2104, which helps to reduce the optical energy loss generated during the propagation of the polarized light along the catadioptric relay optical path 200 and the catadioptric imaging optical path 300.

According to the preferred embodiment of the present invention, as shown in fig. 3, the relay system 20 further includes a relay lens assembly 23, wherein the relay lens assembly 23 is disposed between the relay incident surface 2101 of the relay polarization beam splitting system 21 and the light source system 10, and is used for adjusting the convergence degree of the S-polarized light from the light source system 10 so that the S-polarized light satisfies the illumination area required by the display unit 40.

Furthermore, in the preferred embodiment according to the present invention, as shown in fig. 4, the relay system 20 further includes a relay polarization filtering unit 24, wherein the relay polarization filtering unit 24 is disposed between the relay lens assembly 23 and the relay incident surface 2101 of the relay polarization beam splitting system 21 for filtering stray light (i.e. non-S-polarized light) in the S-polarized light from the light source system 10, so as to ensure that the S-polarized light incident from the relay incident surface 2101 has high purity, which helps to improve the imaging quality of the micro projection light engine 1.

Illustratively, the relay polarization filtering unit 24 may be, but is not limited to being, implemented as an S-polarizer for allowing only S-polarized light to pass therethrough and blocking P-polarized light or/and other parasitic light from passing therethrough to filter P-polarized light or/and other parasitic light in the S-polarized light from the light source system 10.

It should be noted that in other examples of the present invention, an 1/4 wave plate (not shown) is further disposed between the display unit 40 and the relay polarization beam splitting system 21 of the relay system 20, so as to improve the contrast of the system, which helps to further improve the imaging quality of the micro projection light engine 1.

However, the conventional micro projection light engine generally includes a light source system, a relay lens set, a display chip, and a projection imaging system, wherein the relay lens set is located in an emission path of the light source system, and the display chip and the projection imaging system are located on opposite sides of the relay lens set, so as to define a linear imaging light path through the display chip and the projection imaging system. In order to obtain a high-quality projection effect, the existing micro projection light engine needs to provide a long enough imaging light path, which also results in a large size and volume of the existing micro projection light engine, and is difficult to meet the market demand for a small-volume micro projection light engine, and especially cannot be widely applied and popularized in the fields of augmented reality, near-eye display, wearable and the like.

Therefore, in the preferred embodiment of the present invention, the imaging system 30 includes an imaging polarization beam splitting system 31 and an imaging catadioptric system 32, wherein the imaging catadioptric system 32 is configured to refract the polarized light carrying the image information emitted from the imaging polarization beam splitting system 31 back to the imaging polarization beam splitting system 31 to define another portion of the catadioptric imaging optical path 300 within the imaging system 30, so that the micro-projection light engine 1 can project the polarized light carrying the image information along the catadioptric imaging optical path 300. In this way, the catadioptric imaging optical path 300 enables the imaging system 30 to provide a sufficiently long imaging optical path in a small volume, so as to reduce the volume or size of the micro projection light engine 1 while ensuring a high imaging quality of the micro projection light engine 1, which helps meet the market demand for a small-volume micro projection light engine.

Specifically, as shown in fig. 2 and 3, the imaging catadioptric system 32 of the imaging system 30 includes an imaging light conversion element 321 and an imaging light reflection element 322, wherein the imaging light conversion element 321 is disposed between the imaging light reflection element 322 and the imaging polarization beam splitting system 31. The imaging light reflection element 322 is configured to reflect the P or S polarized light carrying the image information emitted from the imaging polarization beam splitting system 31 back to the imaging polarization beam splitting system 31, so that the P or S polarized light carrying the image information passes through the imaging light conversion element 321 twice. The imaging light conversion element 321 is configured to convert the P or S polarized light carrying the image information passing through twice into S or P polarized light carrying the image information.

It is noted that in the preferred embodiment of the present invention, the imaging light conversion element 321 can be, but is not limited to being, implemented as an 1/4 wave plate; the imaging light reflecting element 322 may be implemented as, but is not limited to, a concave mirror. Of course, in other examples of the present invention, the imaging light conversion element 321 may also be implemented as another type of wave plate or light conversion element as long as it can convert the P or S polarized light carrying the image information passing twice into S or P polarized light carrying the image information; the imaging light reflection element 322 may also be implemented as another type of mirror or light reflection element, as long as it can reflect the P or S polarized light carrying the image information emitted from the imaging polarization beam splitting system 31 back to the imaging polarization beam splitting system 31, so that the P or S polarized light carrying the image information passes through the imaging light conversion element 321 twice, which is not further limited in the present invention.

In addition, the imaging polarization beam splitting system 31 of the imaging system 30 is used for reflecting the S-polarized light carrying the image information to change the propagation direction of the S-polarized light carrying the image information, and allowing the P-polarized light carrying the image information to pass through without changing the propagation direction of the P-polarized light carrying the image information. In this way, the other portion of the catadioptric imaging optical path 300 can be designed reasonably according to the above-mentioned characteristics of the imaging polarization beam splitting system 31 and the imaging catadioptric system 32 to achieve a sufficiently long imaging optical path in a small volume, so as to further reduce the volume or size of the micro-projection light engine 1 while ensuring a high imaging quality of the micro-projection light engine 1.

Illustratively, as shown in fig. 5A, the imaging polarization beam splitting system 31 of the imaging system 30 has an imaging entrance surface 3101, an imaging exit surface 3102 perpendicular to the imaging entrance surface 3101, and an imaging catadioptric surface 3103 parallel to the imaging entrance surface 3101, wherein the imaging light conversion element 321 of the imaging catadioptric system 32 is disposed between the imaging light reflection element 322 of the imaging catadioptric system 32 and the imaging catadioptric surface 3103 of the imaging polarization beam splitting system 31 to define the another portion of the catadioptric imaging path 300 through the imaging polarization beam splitting system 31 and the imaging light reflection element 322 of the imaging catadioptric system 32.

Thus, when the P-polarized light carrying image information enters the imaging polarization beam splitting system 31 from the imaging entrance surface 3101, the P-polarized light carrying image information passes through the imaging polarization beam splitting system 31 to exit from the imaging catadioptric surface 3103; then, the P-polarized light carrying image information emitted from the imaging mirror surface 3103 is reflected by the imaging light reflecting element 322 back to the imaging mirror surface 3103, so that the P-polarized light carrying image information passes through the imaging light converting element 321 twice; at the same time, the P-polarized light carrying the image information is converted into S-polarized light carrying the image information by the imaging light conversion element 321, so that the converted S-polarized light carrying the image information is incident on the imaging polarization beam splitting system 31 from the imaging reflection surface 3103; finally, the S-polarized light carrying the image information incident from the imaging mirror surface 3103 is reflected by the imaging polarization beam splitting system 31 to exit from the imaging exit surface 3102 for projection imaging, thereby achieving the effect of projection imaging the P-polarized light carrying the image information along the other part of the catadioptric imaging optical path 300.

In other words, in the imaging system 30, the other portion of the catadioptric imaging optical path 300 first extends from the imaging entrance surface 3101 of the imaging polarizing beam splitting system 31 to the imaging refractive surface 3103 of the imaging polarizing beam splitting system 31; the catadioptric imaging optical path 300 is then refracted by the imaging catadioptric system 32 to extend toward the imaging entrance face 3101 of the imaging polarizing beam splitting system 31; finally, the catadioptric imaging optical path 300 is reflected by the imaging polarization beam splitting system 31 to extend to the imaging exit surface 3102 of the imaging polarization beam splitting system 31 in a bending manner, so that the P-polarized light carrying the image information can propagate along the catadioptric imaging optical path 300 in a bending manner to project an image, thereby achieving a sufficiently long imaging optical path in a small space.

It should be noted that the catadioptric imaging optical path 300 includes an imaging optical path between the display unit 40 and the imaging system 30 and an imaging optical path in the imaging system 30, wherein the imaging optical path between the display unit 40 and the imaging system 30 extends from the display unit 40 to the relay exit surface 2102 in a bending manner, then extends from the relay exit surface 2102 to the imaging entrance surface 3101 in a straight line, and the imaging optical path in the imaging system 30 extends from the imaging entrance surface 3101 to the imaging exit surface 3102 in a catadioptric manner, so as to form the catadioptric imaging optical path 300.

More specifically, as shown in fig. 3 and 5A, the imaging polarization beam splitting system 31 of the imaging system 30 includes a first imaging right-angle prism 311, a second imaging right-angle prism 312, and an imaging polarization beam splitting film 313, wherein the imaging polarization beam splitting film 313 is disposed between the inclined surface of the first imaging right-angle prism 311 and the inclined surface of the second imaging right-angle prism 312 to form the imaging polarization beam splitting system 31 having a rectangular structure. The imaging polarization beam splitting film 313 serves to allow the P-polarized light carrying the image information to pass therethrough, and to reflect the S-polarized light carrying the image information to turn the S-polarized light carrying the image information. A rectangular surface of the first imaging right-angle prism 311 is defined as the imaging incident surface 3101 of the imaging polarization beam splitting system 31, and two rectangular surfaces of the second imaging right-angle prism 312 are defined as the imaging emergent surface 3102 and the imaging reverse surface 3103 of the imaging polarization beam splitting system 31, respectively, and the imaging emergent surface 3102 is perpendicular to the imaging incident surface 3101 and the imaging reverse surface 3103.

Thus, the P-polarized light carrying image information incident from the image formation incident surface 3101 can transmit through the image formation polarization beam splitting film 313 to pass through the image formation polarization beam splitting system 31 to exit from the image formation reverse surface 3103; then, the P-polarized light carrying the image information and emitted from the imaging reflecting surface 3103 is converted into S-polarized light carrying the image information by the imaging catadioptric system 32, and the S-polarized light carrying the image information is reflected to the imaging reflecting surface 3103; finally, the S-polarized light carrying image information incident from the image-forming reverse surface 3103 is reflected by the image-forming polarization beam splitting film 313 of the image-forming polarization beam splitting system 31 to be emitted from the image-forming exit surface 3102 to be projected for image formation. In other words, the other portion of the catadioptric imaging optical path 300 extends from the imaging entrance surface 3101 to the imaging reverse surface 3103 first, extends from the imaging reverse surface 3103 to the imaging polarization beam splitting film 313 and then extends from the imaging polarization beam splitting film 313 to the imaging exit surface 3102, so as to extend the length of the catadioptric imaging optical path 300 by catadioptric manner, which helps to reduce the volume or size of the micro-projection light engine 1 while ensuring the projection quality of the micro-projection light engine 1.

It is noted that the imaging polarization beam splitter film 313 can be implemented as, but not limited to, a PBS film for allowing P-polarized light carrying image information to pass through, but preventing S-polarized light carrying image information from passing through and reflecting S-polarized light carrying image information to change the propagation direction of S-polarized light carrying image information.

Preferably, the first and second imaging right-

angle prisms

311 and 312 are each implemented as a isosceles right-angle prism such that the angle between the imaging polarization beam splitter film 313 and the imaging incident surface 3101 is 45 degrees. In this way, the angle between the imaging polarization beam splitter film 313 and the imaging exit surface 3102 and the imaging catadioptric surface 3103 is also 45 degrees, so that the S-polarized light carrying image information that is perpendicularly incident on the imaging catadioptric surface 3103 is reflected by the imaging polarization beam splitter film 313 to perpendicularly exit the imaging exit surface 3102, which helps to reduce the loss of light energy generated by the polarized light during propagation along the catadioptric imaging optical path 300.

Further, in the preferred embodiment of the present invention, as shown in fig. 3 and fig. 5A, the imaging system 30 further includes an imaging conversion unit 33, wherein the imaging conversion unit 33 is disposed between the imaging entrance surface 3101 of the imaging polarization beam splitting system 31 and the relay exit surface 2102 of the relay system 20, and is configured to convert the S-polarized light carrying the image information from the relay system 20 into the P-polarized light carrying the image information, so that the P-polarized light carrying the image information enters the imaging polarization beam splitting system 31 from the imaging entrance surface 3101 and propagates along the another portion of the catadioptric imaging optical path 300.

By way of example, the imaging conversion unit 33 may be implemented, but is not limited to, as an 1/2 wave plate for converting the S-polarized light carrying image information into the P-polarized light carrying image information. Of course, in other examples of the present invention, the imaging conversion unit 33 may also be implemented as a pair of 1/4 wave plates which are overlapped to convert the S-polarized light carrying the image information into the P-polarized light carrying the image information through the two 1/4 wave plates.

According to the preferred embodiment of the present invention, as shown in fig. 5A, the imaging system 30 further includes an imaging lens assembly 34, wherein the imaging lens assembly 34 includes a first imaging lens group 341, and the first imaging lens group 341 is disposed on the imaging exit surface 3102 of the imaging polarization beam splitting system 31 for adjusting the convergence degree of the S-polarized light carrying the image information emitted from the imaging exit surface 3102 so as to satisfy the projection requirement of the micro projection light engine 1.

Further, as shown in fig. 3 and fig. 5A, the imaging lens assembly 34 further includes a second imaging lens group 342, wherein the second imaging lens group 342 is disposed between the imaging conversion unit 33 and the relay system 20, and is used for adjusting the convergence degree of the S-polarized light carrying the image information from the relay system 20, so as to reduce the convergence burden of the first imaging lens group 341 and reduce the thickness of the first imaging lens group 341. It is understood that in other examples of the present invention, the second imaging lens assembly 342 may also be disposed between the imaging conversion unit 33 and the imaging incident plane 3101 of the imaging polarization beam splitting system 31 for adjusting the degree of convergence of the P-polarized light carrying the image information converted by the imaging conversion unit 33.

In addition, in the preferred embodiment according to the present invention, as shown in fig. 5A, the imaging system 30 further includes an imaging polarization filtering unit 35, wherein the imaging polarization filtering unit 35 is disposed between the imaging conversion unit 33 and the imaging incident plane 3101 of the imaging polarization beam splitting system 31, and is used for filtering stray light (non-P-polarized light) in the P-polarized light carrying the image information converted by the imaging conversion unit 33, so as to ensure that the P-polarized light carrying the image information incident from the imaging incident plane 3101 has higher purity, which is helpful for improving the imaging quality of the micro projection light engine 1.

Illustratively, the imaging polarization filtering unit 35 may be, but is not limited to being, implemented as a P-polarizer for allowing only P-polarized light carrying image information to pass therethrough and blocking S-polarized light carrying image information from passing therethrough to filter S-polarized light or other stray light in the P-polarized light carrying image information converted by the imaging conversion unit 33.

Fig. 5B shows a modified embodiment of the imaging system 30 according to the preferred embodiment of the present invention, wherein the imaging polarization beam splitting system 31 of the imaging system 30 has an imaging entrance surface 3101, an imaging exit surface 3102 perpendicular to the imaging entrance surface 3101, and an imaging catadioptric surface 3103 perpendicular to the imaging entrance surface 3101, wherein the imaging light conversion element 321 of the imaging catadioptric system 32 is disposed between the imaging light reflection element 322 of the imaging catadioptric system 32 and the imaging catadioptric surface 3103 of the imaging polarization beam splitting system 31 to define the other portion of the catadioptric imaging path 300 through the imaging polarization beam splitting system 31 and the imaging light reflection element 322 of the imaging catadioptric system 32.

Thus, in this modified embodiment of the present invention, it is not necessary to first convert the S-polarized light carrying the image information from the relay system 20 into the P-polarized light carrying the image information by the imaging conversion element 33, and then make the P-polarized light carrying the image information enter the imaging polarization beam splitting system 31 from the imaging entrance surface 3101, but the S-polarized light carrying the image information from the relay system 20 directly enters the imaging polarization beam splitting system 31 from the imaging entrance surface 3101, so as to further reduce the size of the micro projection light engine 1.

In other words, since the polarized light incident from the imaging incident surface 3101 is the S-polarized light carrying the image information, and the polarized light from the relay system 20 is also the S-polarized light carrying the image information, in this modified embodiment of the present invention, the imaging system 30 does not need to provide any imaging conversion unit 33, so that the S-polarized light carrying the image information from the relay system 20 can be incident from the imaging incident surface 3101 to the imaging polarization beam splitting system 31 without conversion.

Illustratively, as shown in fig. 5B, first, the S-polarized light carrying image information incident from the imaging incident surface 3101 is reflected by the imaging polarization beam splitting system 31 to exit from the imaging catadioptric surface 3103; then, the S-polarized light carrying the image information and emitted from the imaging mirror surface 3103 is reflected by the imaging light reflecting element 322 back to the imaging mirror surface 3103, so that the S-polarized light carrying the image information passes through the imaging light converting element 321 twice; at the same time, the S-polarized light carrying the image information is converted into P-polarized light carrying the image information by the imaging light conversion element 321, so that the converted P-polarized light carrying the image information is incident on the imaging polarization beam splitting system 31 from the imaging reflection surface 3103; finally, the P-polarized light carrying the image information incident from the imaging reverse side 3103 passes through the imaging polarization beam splitting system 31 to exit from the imaging reverse side 3103, so as to realize the effect of projecting and imaging the S-polarized light carrying the image information along the catadioptric imaging optical path 300.

In other words, in this modified embodiment, the two right-angled surfaces of the first imaging right-angle prism 311 are respectively defined as the imaging incident surface 3101 and the imaging catadioptric surface 3103 of the imaging polarization beam splitting system 31, and the right-angled surface of the second imaging right-angle prism 312 is defined as the imaging exit surface 3102 of the imaging polarization beam splitting system 31. In this way, the other portion of the catadioptric imaging optical path 300 first extends from the imaging entrance surface 3101 to the imaging polarization beam splitting film 313, and then extends from the imaging polarization beam splitting film 313 to the imaging catadioptric surface 3102, and then extends from the imaging catadioptric surface 3103 to the imaging exit surface 3102, so as to extend the length of the catadioptric imaging optical path 300 by catadioptric method, which helps to further reduce the volume or size of the micro-projection optical engine 1 while ensuring the projection quality of the micro-projection optical engine 1.

Furthermore, in this modified embodiment, as shown in fig. 5B, the imaging polarization filtering unit 35 of the imaging system 30 is disposed between the second imaging lens group 342 and the imaging incident surface 3101 of the imaging polarization beam splitting system 31, and is used for filtering stray light (i.e., non-S-polarized light) in the S-polarized light carrying image information from the relay system 20, so as to ensure that the S-polarized light carrying image information incident from the imaging incident surface 3101 has high purity, which is helpful for improving the imaging quality of the micro projection light engine 1.

Illustratively, the imaging polarization filtering unit 35 may be, but is not limited to being, implemented as an S-polarizer for allowing only S-polarized light carrying image information to pass through and blocking P-polarized light carrying image information from passing through to filter P-polarized light or other stray light in the S-polarized light carrying image information from the relay system 20.

It should be noted that, according to the preferred embodiment of the present invention, as shown in fig. 1 to fig. 3, the light source system 10 of the micro projection light engine 1 includes at least two light emitting units 11, a color combining system 12 and a polarization conversion system 13, wherein each of the light emitting units 11 is configured to emit monochromatic light, the color combining system 12 is disposed between the at least two light emitting units 11 and the polarization conversion system 13 and configured to combine the monochromatic light emitted by the at least two light emitting units 11 into a combined light, and the polarization conversion system 13 is configured to convert the combined light into the S-polarized light. It will be appreciated that both the monochromatic light and the combined light are implemented as unpolarized light, which typically consists of P-polarized light and S-polarized light.

It is noted that the polarization conversion system 13 can be, but is not limited to be, implemented as a PCS array for converting unpolarized light into S polarized light. Of course, in other examples of the present invention, the polarization conversion system 13 may also be implemented as a PCS array and an 1/2 wave plate, wherein the PCS array is disposed between the 1/2 wave plate and the color combination system 12, wherein the PCS array is used for converting the unpolarized light into P-polarized light, and the 1/2 wave plate is used for converting the P-polarized light into the S-polarized light.

In addition, in the preferred embodiment of the present invention, the color combining system 12 can be, but is not limited to, implemented as a wedge-shaped prism coated with a color selective transmission film for combining two monochromatic lights into one light according to a ratio requirement. Of course, in other examples of the present invention, the color combining system 12 can also be implemented as an X color combining prism or a color combining sheet for combining multiple monochromatic lights into one light, which is not further limited by the present invention.

Further, as shown in fig. 1 and 3, the light source system 10 further includes at least two collimating systems 14 and an dodging system 15. Each of the collimating systems 14 is disposed between the corresponding light emitting unit 11 and the color combining system 12, and is used for collimating the monochromatic light emitted by the light emitting unit 11. The light uniformizing system 15 is disposed between the color combining system 12 and the polarization conversion system 13, and is configured to uniformize the combined light. It will be appreciated by those skilled in the art that the collimating system 14 may be, but is not limited to being, implemented as a collimating lens; the light homogenizing system 15 may be implemented as, but not limited to, a fly-eye or a Micro-lens array (MLA).

According to another aspect of the present invention, as shown in fig. 6A and 6B, the present invention further provides a near-eye display device. As shown in fig. 6A, the near-eye display device includes a waveguide 500 and any one of the above-mentioned miniature projection light engines 1, wherein the miniature projection light engine 1 is configured to project polarized light carrying image information to the waveguide 500, so as to project the polarized light carrying image information into human eyes through the waveguide 500.

It is noted that in fig. 6A, the micro-projection light engine 1 and the human eye are located on the same side of the waveguide 500. Of course, as shown in fig. 6B, in another example of the present invention, the micro-projection light engine 1 and the human eye may also be respectively located at opposite sides of the waveguide 500 (i.e. different sides of the waveguide 500), and it is also possible to project the polarized light carrying the image information into the human eye, and the present invention is not limited to this, and only needs to ensure that the polarized light carrying the image information from the micro-projection light engine 1 is projected into the human eye through the waveguide 500. Further, it will be understood by those skilled in the art that the type of the near-eye display device is not limited, for example, the near-eye display device may be a head-mounted display device such as AR glasses or the like.

It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.

Claims

1. A miniature projection light engine for a near-eye display device, comprising:

a relay system, wherein the relay system is disposed between the light source system, the display unit and the imaging system, and the light source system and the imaging system are respectively located at opposite sides of the relay system, wherein the relay system is configured to change a propagation direction of polarized light from the light source system so that the polarized light propagates to the display unit; wherein the relay system is further configured to change a propagation direction of the polarized light carrying the image information from the display unit so that the polarized light carrying the image information can propagate to the imaging system along the predetermined direction;

the imaging system comprises an imaging polarization beam splitting system and an imaging catadioptric system, wherein the imaging polarization beam splitting system is positioned between the imaging catadioptric system and the relay system, the imaging catadioptric system is used for reflecting polarized light carrying image information and emitted from the imaging polarization beam splitting system back to the imaging polarization beam splitting system so as to define a catadioptric imaging optical path forming the imaging system through the relay system and the imaging system, and the miniature projection light engine can project the polarized light carrying the image information along the catadioptric imaging optical path;

wherein the imaging system further comprises an imaging lens assembly, wherein the imaging lens assembly comprises a first imaging lens group and a second imaging lens group, wherein the first imaging lens group is disposed between the relay system and the imaging polarization beam splitting system, and the second imaging lens group is disposed at an imaging exit surface of the imaging polarization beam splitting system.

2. The micro-projection light engine of claim 1, wherein the relay system comprises a relay polarization beam splitting system and a relay catadioptric system, wherein the relay polarizing beam splitting system is disposed between the light source system and the imaging system, and the display unit and the relay catadioptric system are respectively positioned at two opposite sides of the relay polarization beam splitting system, wherein the display unit is further adapted to reflect the polarized light carrying image information back to the relay polarizing beam splitting system, and the relay catadioptric system is for refracting the polarized light emerging from the relay polarization beam splitting system back to the relay polarization beam splitting system, to define a catadioptric relay optical path forming the relay system between the light source system and the display unit, such that the polarized light can propagate along the catadioptric relay optical path to the display unit.

3. The micro-projection light engine of claim 2, wherein the relay catadioptric system comprises a relay light conversion element and a relay light reflection element, wherein the relay light conversion element is located between the relay polarization beam splitting system and the relay light reflection element, wherein the relay light reflection element is configured to reflect the polarized light emitted from the relay polarization beam splitting system back to the relay polarization beam splitting system so that the polarized light passes through the relay light conversion element twice, and wherein the relay light conversion element is configured to convert the polarized light passing through twice into polarized light having another polarization state.

4. The micro projection light engine of claim 3 wherein the relay light conversion element is an 1/4 waveplate and the relay light reflecting element is a concave mirror.

5. The micro-projection light engine of claim 4, wherein the relay polarization beam splitting system comprises a first relay right-angle prism, a second relay right-angle prism, and a relay polarization beam splitting film, wherein the relay polarization beam splitting film is disposed between the inclined plane of the first relay right-angle prism and the inclined plane of the second relay right-angle prism to form the relay polarization beam splitting system having a rectangular cross section, wherein the relay polarization beam splitting film is configured to allow P-polarized light to pass therethrough and reflect S-polarized light to change the propagation direction of the S-polarized light.

6. The micro projection light engine of claim 5, wherein the relay polarizing beam splitting film is a PBS film.

7. The micro-projection light engine of claim 5, wherein the relay polarization beam splitting system has a relay entrance surface, a relay exit surface parallel to the relay entrance surface, a relay reflection surface perpendicular to the relay entrance surface, and a relay display surface perpendicular to the relay entrance surface, wherein the light source system corresponds to the relay entrance surface; wherein the relay inflexion system corresponds to the relay inflexion surface; wherein the display unit corresponds to the relay display surface; wherein the imaging system corresponds to the relay exit face.

8. The micro projection light engine of claim 7, wherein the relay entrance surface and the relay display surface of the relay polarization beam splitting system intersect at the relay polarization beam splitting film, and the relay exit surface and the relay reflection surface of the relay polarization beam splitting system intersect at the relay polarization beam splitting film, such that S-polarized light from the light source system is reflected by the relay polarization beam splitting film to propagate from the relay entrance surface to the relay reflection surface while being bent, and then after being converted into P-polarized light by the relay reflection system and being bent back to the relay reflection surface, the P-polarized light passes through the relay polarization beam splitting film to propagate from the relay reflection surface to the display unit at the relay display surface.

9. The micro projection light engine of claim 8, wherein the relay system further comprises a relay lens assembly, wherein the relay lens assembly is disposed between the relay entrance surface of the relay polarizing beam splitting system and the light source system for adjusting the degree of convergence of the polarized light from the light source system.

10. The micro-projection light engine of claim 9, wherein the relay system further comprises a relay polarization filter unit, wherein the relay polarization filter unit is disposed between the relay lens assembly and the relay entrance surface of the relay polarization beam splitting system for filtering stray light in the S-polarized light.

11. The micro-projection light engine of claim 10, wherein the relay polarization filtering unit is an S-polarizer.

12. The micro-projection light engine of any one of claims 8 to 11, wherein the imaging catadioptric system comprises an imaging light conversion element and an imaging light reflection element, wherein the imaging light conversion element is located between the imaging light reflection element and the imaging polarization beam splitting system, wherein the imaging light reflection element is configured to reflect the polarization light carrying image information emitted from the imaging polarization beam splitting system back to the imaging polarization beam splitting system, so that the polarization light carrying image information passes through the imaging light conversion element twice, and wherein the imaging light conversion element is configured to convert the polarization light carrying image information passing twice into polarization light carrying image information having another polarization state.

13. The micro projection light engine of claim 12 wherein the imaging light conversion element is an 1/4 wave plate and the imaging light reflection element is a concave mirror.

14. The micro-projection light engine of claim 13, wherein the imaging polarization beam splitting system comprises a first imaging right-angle prism, a second imaging right-angle prism, and an imaging polarization beam splitting film, wherein the imaging polarization beam splitting film is disposed between the inclined plane of the first imaging right-angle prism and the inclined plane of the second imaging right-angle prism to form the imaging polarization beam splitting system with a rectangular cross section, wherein the imaging polarization beam splitting film is configured to allow P-polarized light carrying image information to pass through and reflect S-polarized light carrying image information to turn the S-polarized light carrying image information.

15. The micro-projection light engine of claim 14, wherein the imaging polarizing beam splitting system has an imaging entrance face, the imaging exit face perpendicular to the imaging entrance face, and an imaging reflection face perpendicular to the imaging entrance face, wherein the imaging catadioptric system corresponds to the imaging catadioptric surface and the relay system corresponds to the imaging entrance surface, wherein the catadioptric imaging optical path extends from the relay display surface to the relay exit surface in a bending manner, and then extends from the relay exit surface to the imaging entrance surface, then, the refraction and reflection type imaging optical path is reflected by the imaging polarization beam splitting film to extend from the imaging incidence surface to the imaging refraction and reflection surface in a bending way, and finally after being refracted and reflected by the relay refraction and reflection system to the imaging refraction and reflection surface, and then the light passes through the imaging polarization beam splitting film to extend from the imaging refraction and reflection surface to the imaging emergent surface.

16. The micro-projection light engine of claim 15, wherein the imaging system further comprises an imaging polarization filtering unit, wherein the imaging polarization filtering unit is disposed between the relay system and the imaging entrance face of the imaging polarization beam splitting system for filtering stray light in the S-polarized light carrying image information from the relay system.

17. The micro-projection light engine of claim 16, wherein the imaging polarization filtering unit is an S-polarizer.

18. The micro-projection light engine of claim 14, wherein the imaging polarizing beam splitting system has an imaging entrance face, the imaging exit face perpendicular to the imaging entrance face, and an imaging reflection face parallel to the imaging entrance face, wherein the imaging catadioptric system corresponds to the imaging catadioptric surface and the relay system corresponds to the imaging entrance surface, wherein the catadioptric imaging optical path extends from the relay display surface to the relay exit surface in a bending manner, and then extends from the relay exit surface to the imaging entrance surface, then, the refraction and reflection type imaging optical path passes through the imaging polarization beam splitting film to extend from the imaging incidence surface to the imaging refraction and reflection surface, and finally after being refracted and reflected by the imaging refraction and reflection system to the imaging refraction and reflection surface, and then reflected by the imaging polarization beam splitting film to extend from the imaging refraction and reflection surface to the imaging emergent surface in a bending way.

19. The micro projection light engine of claim 18, wherein the imaging system further comprises an imaging conversion unit, wherein the imaging conversion unit is disposed between the imaging entrance surface of the imaging polarization beam splitting system and the relay system for converting S-polarized light carrying image information from the relay system into P-polarized light carrying image information incident from the imaging entrance surface.

20. The micro projection light engine of claim 19 wherein the image conversion unit is an 1/2 waveplate or a pair of 1/4 waveplates.

21. The micro projection light engine of claim 19, wherein the imaging system further comprises an imaging polarization filtering unit, wherein the imaging polarization filtering unit is disposed between the imaging conversion unit and the imaging entrance surface of the imaging polarization beam splitting system for filtering stray light in the image information carrying P-polarized light converted by the imaging conversion unit.

22. The micro-projection light engine of claim 21, wherein the imaging polarization filtering unit is a P-polarizer.

23. The micro projection light engine of claim 22, wherein the light source system comprises at least two light emitting units, a color combining system, and a polarization multiplexing system, wherein each light emitting unit is configured to emit monochromatic light, wherein the color combining system is located between the at least two light emitting units and the polarization multiplexing system, and is configured to combine the monochromatic light emitted by the at least two light emitting units into a combined color light, and wherein the polarization multiplexing system is configured to convert the combined color light into S-polarized light.

24. The micro projection light engine of claim 23, wherein the light source system further comprises at least two collimating systems and an dodging system, wherein each collimating system is disposed between the corresponding light emitting unit and the color combining system for collimating the monochromatic light emitted by the corresponding light emitting unit; the light homogenizing system is arranged between the color combination system and the polarization multiplexing system and is used for homogenizing the color combination light.